Paleontologists have described a brand new species of pachypleurosaur from the Heart Triassic of southwestern China.
The holotype of Dianmeisaurus mutaensis from the Guanling Formation, China: (A) the skeleton in dorsal view; (B) the counterpart of (A). Scale bars – 1 cm. Symbol credit score: Hu et al., doi: 10.1186/s13358-023-00292-4.
Dianmeisaurus mutaensis lived in what’s now China throughout the Anisian age of the Heart Triassic epoch, round 245 million years in the past.
The traditional species is one of those pachypleurosaur, a bunch of primitive sauropterygian reptiles from the Triassic duration.
Those animals resembled aquatic lizards and had small heads, lengthy necks, paddle-like limbs, and lengthy, deep tails.
“The Sauropterygia is probably the most flourishing clade amongst Mesozoic marine reptiles in the case of species variety, and contains the long-lasting Plesiosauria from the Jurassic and Cretaceous and the stem-group Placodontia and Eosauropterygia from the Triassic,” stated Dr. Jun Liu and co-workers from the Hefei College of Era.
“Eosauropterygians had been historically divided into 3 teams, the Pachypleurosauria, the Nothosauroidea, and the Pistosauroidea.”
“This conventional view holds {that a} monophyletic Pachypleurosauria accommodates the sister organization to the clade Eusauropterygia consisting of Nothosauroidea and Pistosauroidea.”
A whole and articulated skeleton of an immature Dianmeisaurus mutaensis used to be present in an deserted quarry this is about 1 km northwest of Muta village in Luxi county, Yunnan province, China.
The skeleton used to be cut up into two portions throughout assortment and ready with pneumatic gear and needles in a paleontological lab.
“The skeleton, embedded within the dark-gray micritic limestone, is composed of an element and its counterpart,” the paleontologists stated.
“The specimen is well-preserved, with a complete period of 99.2 mm (4 inches).”
“Adjoining to the specimen, there are scattered limb and rib bones from different particular person(s), however the restricted data to be had prevents additional identity.”
An artist’s impact of the pachypleurosaur Wumengosaurus. Symbol credit score: Nobu Tamura / CC BY-SA 4.0.
The workforce’s research recovered the brand new species as a sister organization to Dianmeisaurus gracilis, a small pachypleurosaur from the Heart Triassic Luoping biota.
“Dianmeisaurus mutaensis shows a number of automorphic options, together with the postfrontal extending posteriorly to the center of the parietal desk and being excluded from higher temporal fenestra, a stout final dorsal rib shorter than the primary sacral rib, and two sacral vertebrae,” the researchers stated.
“As well as, a singular information matrix used to be compiled to reconsider the interrelationships of eosauropterygians.”
“Phylogenetic research displays the cave in of the monophyly of Eusauropterygia,” they added.
“Pistosauroidea, Majiashanosaurus, and Hanosaurus represent the consecutive sister teams to a monophyletic clade comprising Pachypleurosauria and Nothosauroidea.”
“Moreover, the monophyly of Pachypleurosauria is supported by way of six synapomorphies.”
“Our phylogenetic effects supply additional proof to the japanese Tethys beginning of pachypleurosaurs,” they stated.
“Alternatively, early Anisian pachypleurosaurs from the japanese Tethys area are required to check the biogeographic speculation.”
The findings had been printed within the Swiss Magazine of Palaeontology.
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YW. Hu et al. 2024. A brand new pachypleurosaur (Reptilia: Sauropterygia) from the Heart Triassic of southwestern China and its phylogenetic and biogeographic implications. Swiss J Palaeontol 143, 1; doi: 10.1186/s13358-023-00292-4
